Is severe OHSS associated with adverse pregnancy outcomes? Evidence from a case-control study.

Ovarian hyperstimulation syndrome (OHSS) is a serious and potentially life-threatening complication of fertility treatment. This study evaluated pregnancy outcomes of women hospitalized for severe OHSS. A case-control study was performed of 125 women who were hospitalized due to severe OHSS compared with a control group, consisting of 156 women matched by age and aetiology of infertility, who conceived via IVF and did not develop OHSS. Among women with singleton pregnancies, patients with severe OHSS delivered significantly earlier (37.96 versus 39.11 weeks) and had smaller babies (2854 g versus 3142 g) compared with the matched controls. Similarly, rates of preterm delivery (<34 weeks of gestation: 8.9% versus 0%, P < 0.01; <37 weeks of gestation: 20.5% versus 5.1%, P < 0.01) were significantly increased among patients in the study group. There were no between-group differences in the rates of gestational diabetes, gestational hypertension and intrauterine growth restriction. In contrast, twin pregnancies following OHSS were not significantly different from matched control twins, with regard to the rates of delivery <34 weeks and <37 weeks of gestation, gestational diabetes, gestational hypertension and intrauterine growth restriction. In conclusion, severe OHSS at early gestation is associated with adverse pregnancy outcome only in singleton gestations.